This is very bad and harmful to health. Chinese medicine believes that if you don't pay attention to cold and warmth, cold will invade the body and affect the growth and development of bones. 14 years old is the stage of growth and development, so we should pay more attention to the accumulation of physical quality. If you don't keep warm now, you may get arthritis and other diseases when you get old. So don't think that you will regret it when you are young.